The present invention relates to a device for quality decision of a machining state of an electric spark machine.
In an electric spark machine, a discharging state display unit showing histograms of the quantities, such as discharging voltage, discharging current, and a peak value of the discharging current, for display of a discharging state of an electric spark machine has been disclosed in Japanese Patent Application Laid-Open gazettes (JP-A No. 3-35930); and an electric spark machining monitoring device with a screen displaying physical quantities, for display of an electric spark machining state, such as average machining voltage, average gap voltage, and machining speed has been published in Japanese Patent Application Laid-Open gazettes (JP-A No. 6-8054).
The above discharging state display unit and electric spark machining monitoring device show only physical quantities denoting a discharging state and a machining state. Therefore, an operator is required to make a quality decision with the above displayed values, based on the rules of thumb, in order to perform quality decision of a machining state, to cause wide varieties of quality decisions.
Though the operator is required to properly perform quality decision using a combination of a plurality of physical quantities denoting a machining state, it is considerably difficult for the operator to properly perform the above evaluation.
As another conventional device, a monitoring device for an electric spark machine, which performs the quality decision by display of physical quantities denoting an electric spark machining state such as machining speed, machining voltage, machining current, on and off times of applied voltage, total number of discharges, number of abnormal discharges, abnormal discharging rate, and discharging frequency, and by comparison between the above physical quantities and predetermined values, has been disclosed in Japanese Patent Application Laid-Open gazettes (JP-A No. 7-204942).
In the above monitoring device, the quality decision of the machining state is automatically performed, but the quality decision is not properly performed, as the quality decision of the machining state is performed based on a single physical quantity such as machining speed and machining voltage. The operator is required to make presumption for proper quality decision using the quality decision results based on a single physical quantity in order to perform proper quality decision using a combination of a plurality of physical quantities denoting a machining state.
It is an object t of this invention to provide a device for quality decision of a machining state of an electric spark machine.
The device for quality decision of a machining state of an electric spark machine according to this invention applies voltage in a pulse form to a machining space between an electrode and a workpiece for contour machining by pulse discharging. This device comprises a plurality of machining state detection means each of which detects a physical quantity denoting individual machining states, the physical quantity detected by any one of the machining state detection means being different from the physical quantity detected by any other of the machining state detection means; and a machining state evaluation and quality decision means which synthetically evaluates a machining state and quality decision of the state based on a combination of a results of comparison of the physical quantities detected by the machining state detection means with predetermined standard values for each of the physical quantities.
Thus, each of the plurality of machining state detection means detects physical quantities denoting individual machining states which are different from each other. Furthermore, the machining state evaluation and quality decision means evaluates the machining states synthetically using a combination of comparison results, for physical quantities, between predetermined standard values for each physical quantity and physical quantities detected by the machining state detection means. Then, proper quality decision of the machining state is performed based on the above evaluation.
Moreover, in the above-mentioned device it is preferable that, the physical quantities are machining speed; machining voltage; machining current; on and off times of voltage applied to an electrode; total number of discharges, number of abnormal discharges; abnormal discharging rate; and discharging frequency. In this case, it is preferable that, the machining state evaluation and quality decision means synthetically evaluates the machining states, using a combination of comparison results for at least two of the physical quantities and performs the quality decision of the machining state.
Thus, the machining state evaluation and quality decision means synthetically evaluates a machining state, using a combination of comparison results, which are made between a standard value predetermined for each physical quantity, and a corresponding physical quantity detected by the machining state detection means for at least two of the following physical quantities and the combination of the comparison result between the machining speed and the machining speed standard value, and that between the machining voltage and the machining voltage standard value. The physical quantities being machining speed, machining voltage, machining current, on and off times of the voltage a applied to the electrode, total number of discharges, number of abnormal discharges, abnormal discharging rate, and discharging frequency. Then, the machining state evaluation and quality decision means performs an appropriate quality decision of the machining state.
Furthermore, in the above-mentioned device it is preferable that, the machining state evaluation and quality decision means classifies the ratio of the physical quantities to the corresponding standard values or the variances of the physical quantity with the corresponding standard values based on their amplitudes into many levels, and performs the quality decision of the machining state based on a combination of these levels.
That is, the ratios of physical quantities to the corresponding standard values or the variances between them are classified for each physical quantity by the machining state evaluation and quality decision means, and stepwise quality decision of a machining state is performed using the combination of the classifications.
Moreover, in the above-mentioned device it is preferable that the standard value of each physical quantity is set according to machining trajectory shapes and machining modes.
Thus, according to machining trajectory shapes and machining modes, standard values are properly predetermined to cause more proper quality decision of a machining state.
Furthermore, in the above-mentioned device it is preferable that the machining state evaluation and quality decision means evaluates each physical quantity based on an average value of the physical quantity during a desired time duration.
That is, the machining state evaluation and quality decision means evaluates physical quantities based on the average values for a fixed time duration, and quality decision of a machining states is properly performed based on the above evaluation.
Moreover, in the above-mentioned device it is preferable that the machining state evaluation and quality decision means evaluates each physical quantity based on an average value of the physical quantity during a fixed section of a machining trajectory or during a fixed line segment.
Thus, the machining state evaluation and quality decision means evaluates physical quantities, using average values for a fixed section or a fixed line segment of the machining trajectory, and proper quality decision of a machining state may be performed based on the above evaluation.
Moreover, in the above-mentioned device it is preferable that the machining state evaluation and quality decision means outputs the result of the quality decision of the machining state to an output device, the output device being a display unit or a printer.
Thus, quality decision results of machining states are output to the output device such as a display unit and a printer by the machining state evaluation and quality decision means, and the quality decision results of the machining states may be understood using the display, printout and so on of the quality decision results.
Moreover, in the above-mentioned device it is preferable that the machining state evaluation and quality decision means divides a machining trajectory line for contour machining, which is displayed on a display unit, into a plurality of areas, and gives each color to respective divided areas of the machining trajectory line according to the quality decision results of the machining state.
That is, the machining state evaluation and quality decision means divides the machining trajectory line for contour machining displayed on the displayed device into a plurality of areas, and gives different colors to each divided area of the machining trajectory line according to the quality decision result for the machining, and then, the quality decision results of machining states may be distinguished for each divided area using the above displayed colors.